Ventri-sphere high energy scrubber

ABSTRACT

An improved multiple stage and compact form of venturi type scrubber unit adapted for cleaning gaseous streams laden with extremely fine particulates, with such unit providing a downflow of the gaseous stream through a venturi throat section along with recycle slurry to effect high velocity wetting of entrained particles. The discharge of wetted gas and particles is, in turn, downwardly from an elongated diffuser section or energy regain tube toward a lower slurry collecting zone whereby the gaseous stream flow is caused to reverse 180* and then pass upwardly through loose light weight mobile packing maintained in between vertically spaced apart perforate retainer means to effect particulates and mist removal in the presence of a countercurrently flowing liquid stream being introduced above such removal zone. A preferred embodiment utilizes a flexible venturi throat section which is mechanically adjustable to provide a variable cross-sectional area that will be changed responsive to variations in gas and liquid volumes and in turn sustain a substantially constant pressure drop across such throat section. Also, the unit may incorporate a plurality of sloping vane means above the mobile packing zone to effect further liquid deentrainment from the clean gas stream prior to its discharge from the unit.

United States Patent Tomany et al.

[451 Feb. 26, 1974 VENTRI-SPHERE HIGH ENERGY SCRUBBER [75] Inventors:James P. Tomany, Darten; George H. Cash, Wilton, both of Conn.

[73] Assignee: Universal Oil Products Company, Des Plaines, Ill.

[22] Filed: Dec. 21, 1972 [21] Appl. No.: 317,346

Related US. Application Data [60] Division of Ser. No. 824,365, May 5,1969, which is a continuation of Ser. No. 625,260, March 22, 1967,abandoned.

[52] US. Cl 55/91, 55/93, 55/95, 55/223, 55/233, 55/241, 55/257,261/DIG. 54, 261/62, 261/94, 261/112 [51] Int. Cl B01d 47/02 [58] Fieldof Search 55/90-95, 223, 55/226, 227, 233, 240, 241, 259, 260, 257;261/DIG. 54, 79.1, 94, 95,112, 115, 62

[56] References Cited UNITED STATES PATENTS 7 2,484,277 10/1949 Fisher55/223 3,302,372 2/1967 Hynson et a1 55/71 3,085,793 4/1963 Pike et a1261/112 FOREIGN PATENTS OR APPLICATIONS 45,132 11/1961 Poland 26l/DIG.54

Primary ExaminerBernard Nozick Attorney, Agent, or Firm.lames R.Hoatson, Jr; Philip T. Liggert 5 7] ABSTRACT An improved multiple stageand compact form of venturi type scrubber unit adapted for cleaninggaseous streams laden with extremely fine particulates, with such unitproviding a downflow of the gaseous stream through a venturi throatsection along with recycle slurry to effect high velocity wetting ofentrained particles. The discharge of wetted gas and particles is, inturn, downwardly from an elongated diffuser section or energy regaintube toward a lower slurry collecting zone whereby the gaseous streamflow is caused to reverse 180 and then pass upwardly through loose lightweight mobile packing maintained in between vertically spaced apartperforate retainer means to effect particulates and mist removal in thepresence of a counter-currently flowing liquid stream being introducedabove such removal zone. A preferred embodiment utilizes a flexibleventuri throat section which is mechanically adjustable to provide avariable crosssectional area that will be changed responsive tovariations in gas and liquid volumes and in turn sustain a substantiallyconstant pressure drop across such throat section. Also, the unit mayincorporate a plurality of sloping vane means above the mobile packingzone to effect further liquid de-entrainment from the clean gas streamprior to its discharge from the unit.

5 Claims, 2 Drawing Figures 8/11 n Recycle Cleaned Gus OuI/l/PATENTEnrtazs m4 3, 793509 Figur 8/0 rry fie ayc/e Figure, 2

' Variable Area Flexible.

T/Iraa! Seal/an VENTlRl-SPHERE HIGH ENERGY SCRUBBER This is a divisionof application Ser. No. 824,365, filed May 5, 1969, which in turn is acontinuation of application Ser. No. 625,260, filed on March 22, 1967,now abandoned.

The present invention is directed to an improved high energy venturitype scrubber unit adapted for removing extremely fine particulates froma laden gaseous stream. More specifically, there is provided a firststage downflow through a venturi section with wetted particles beingdischarged into a lower slurry collecting section and then a reverseflow up through a second stage scrubber zone having a light weightmobile packing to provide surface area for countercurrent scrubbing inthe presence of a descending sprayed liquid.

It is recognized that the use of venturi type scrubbers is not new forcleaning particle laden gaseous streams, particularly since they are ofadvantage in effecting an efficient wetting of the entrained particlesin a restricted area where the gas velocity is high. Actually, the highvelocity effect of the venturi results in a breakdown of the liquidstream being introduced just ahead of the venturi throat section suchthat there is a highly efficient contacting and liquid entrapment of allof the entrained particles. The venturi unit is of advantage for boththe plus-micron and sub-micron particles; however, greater pressure dropconditions may be required through the venturi for the smaller submicronsize particulates. The pressure drop can be varied by changing the gasvelocity and/or changing the liquid injection rate. Alternatively, therecan be a changing of the size of the venturi throat section to suitvariations in gas or liquid flow rates or in the size and nature of theentrained particulates.

The presently known commercial forms of venturi scrubbers are generallyof a single stage type of operation or discharge into cyclone separatorswhich must handle a droplet laden stream. In some cases, mesh or blankettype mist extractor sections are used downstream from the venturi andseparator sections. However, blanket type extraction sections aresubject to plugging and all of the related problems encountered withfixed bed packing or filter arrangements.

SUMMARY OF THE INVENTION It may be considered a principal object of thepresent invention to provide a two-stage particulate scrubbing system,where a down-flow high energy venturi scrubber section is used in afirst stage and an up flow provided in a second stage to have the gaspass countercurrently to a descending liquid flow in the presence ofrandomly moving light weight contact elements, all within a unit designarrangement.

It is also an object of the present invention to provide a two-stageventuri-mobile element scrubber system which incorporates a flexibleventuri throat section whereby the cross-sectional area thereof can bechanged to maintain a substantially constant, or desired, pressure dropthrough the venturi stage for variation in operating conditions.

In a broad embodiment, the present invention provides a two-stageventuri-scrubber unit for effecting the removal of finely dividedparticulates from a waste gas stream, and comprises in combination, avertically disposed housing having an upper ladened-gas inletdischarging downwardly into a depending funnel section connecting to arestricted area venturi throat section, the upper end portion of saidfunnel section being spaced from the lower end of said inlet and havinga pcripheral weir adapted to provide liquid overflow into said funnelsection from encompassing liquid distributing trough means, liquid inletmeans to the latter to maintain a liquid level therein, an open-endedventuri diffuser section or energy regain tube extending downwardly fromsaid venturi throat section and discharging into a lower liquidretaining sump section, spaced apart horizontally disposed perforatemembers positioned above the lower end of said venturi diffuser sectionand adjacent to the latter in said housing, said members holding amultiplicity of low density movable contact elements adapted to providea second stage scrubbing and particulates and mist extraction sectionfor the gaseous stream flow after it has reversed its direction from thelower end of said diffuser section and from said sump section, liquiddistribution means positioned above the upper end portion of said mistextraction section to effect countercurrent gas-liquid flow in suchsection over said contact elements therein, cleaned-gas outlet meansfrom said housing spaced above said extraction section, and slurrywithdrawal means from said sump section in the lower end of saidhousing.

In a preferred and more specific embodiment, there is provided aflexible venturi throat, which may be made of rubber or other flexiblematerial, and mechanically movable throat restricting means which ismounted adjacent to, or encompassing the throat section, such that theremay be the desired automatic adjustment thereof in order to vary thecross-sectional area of the venturi throat section. Generally, as notedbriefly hereinbefore, in order to maintain the most efficient operationof the unit, it is desirable to maintain a substantially constantpressure drop through the venturi section, or have means for adjustingpressure drop to suit changing operating conditions. Thus, amechanically movable throat adjustment means is made operable responsiveto changes in gas and liquid volumes passing through the unit so as toobtain a substantially constant pressure drop through the throatsection. Alternatively, with sub-micron size entrained particulates, itmay be necessary to have higher pressure drop through the venturisection so as to insure greater atomization of entrained liquid andimproved wetting of the fine particulates through the venturi section.As a result, a flexible variable sized throat section permits a rapidadjustment in the system operation which will provide a greater pressuredrop through the venturi section to in turn accommodate a gas flowcarrying extremely fine, sub-micron size particles.

In the second stage scrubber section, where there is an upward gaseousflow moving countercurrently to a descending liquid flow through acontact bed of movable contact elements, there are preferably used lightweight or low density elements which have considerable surface area. Forexample, such elements may comprise spherical polyethylene balls wherebythey are readily made fluidizable and can move in random motion betweenthe upper and lower perforate plates defining the second stage scrubbingzone. A preferred arrangement also provides that the light weightfluidizable contact elements, plastic spheres, or whatever, shall fillthe contacting section to less than 50 percent of its depth when theyare in a non-fluidized state, such that there is adequate free-boardspace in the entire section to permit a random, turbulent fluidizedaction for all of the contact elements in the moving bed thereof.

Still another feature for an improved preferred embodiment of thepresent two-stage type of venturiscrubber, is the utilization of aspinner section" above and downstream from the upper end of the zonecontaining the mobile contact elements such that any entrained liquidcarrying upwardly with the gas flow stream will be caused to be thrownagainst the inner wall of the housing of conduit means carrying aresulting spiralling gas flow upwardly to an outlet duct. Generally, themeans providing for the spinning of the gas stream in a spiralling flowpath may comprise a plurality of angularly positioned vanes which willbring about the desired spiral flow and spin out the entrained liquiddroplets.

Reference to the accompanying drawing and the following descriptionthereof will serve to illustrate diagrammatically one embodiment of thepresent improved high energy venturi-scrubber system and additionaladvantages which may be obtained in connection therewith by providing afirst stage down flow venturi section and a reverse up-flow through amovable packing second state scrubbing section.

DESCRIPTION OF THE DRAWING FIG. 1 of the drawing is a sectionalelevational view indicating one simplified embodiment of the improvedhigh energy two-stage venturi-scrubbing system.

FIG. 2 of the drawing indicates in a partial sectional view and in adiagrammatic manner the utilization of automatically movable pistonmeans to vary the crosssectional area through a flexible throat sectionof the unit.

Referring now particularly to FIG. 1 of the drawing there is indicated avertically oriented combined unit having a flanged inlet means 1 for aparticle laden stream and adapted to feed downwardly into a funnelshaped venturi inlet section 2 which in turn feeds into venturi throatsection 3 and thence into diffuser section 4. The latter is shown to bepositioned substantially axially within a vertically elongated housingsection 5 which has a conically shaped lower end portion 6 to provide aliquid or slurry collection section 7. The lower end of the housing conesection 6 is provided with a slurry outlet means 8, while the upperportion of the housing 5 is provided with a top closure plate 9 whichencompasses the diffuser section 4. Also, there is indicated an upperside outlet means 10 from housing 5 for the removal of the cleaned gasstream from the unit.

Various means or systems have been provided in combination withventuri-scrubber units to effect the introduction of a liquid streaminto the funnel inlet section of the venturi or directly into the throatsection thereof; however, a preferred arrangement provides for theuniform introduction of a liquid slurry stream over the entire venturifunnel section 2 so as to preclude the adherence or sticking of anyparticulates within the inlet section of the venturi. In the embodimentof FIG. 1 there is shown a slurry recycle line 11 feeding into a liquidreservoir section 12 such that there may be a 360 flow of liquid over anotched weir member 13 which is indicated as an upper extension offunnel section 2. Thus, in the operation unit, there will be acontinuous flow of liquid down over the inside wall of venturi inletsection 2 and into the restricted area of venturi throat section 3. Atthis restricted area entrance to the venturi throat, the liquid orslurry and the laden gaseous stream will meet and proceed through thethroat section under high pressure conditions. As a result, liquiddroplets are formed and are caused to move rapidly with high velocityaction from the gas stream such that there is instant saturationthereof. Also, there is a reduction in the temperature of such streamwhere it is being introduced as a hot gas. In any case, the entrainedfinely divided particles are in effect forced into contact with waterparticles or droplets such that all of the entrained particulates aredirectly wetted and caused to subsequently agglomerate.

Once the laden gas stream and saturated particles leave the venturithroat section and carry down through the diffuser tube there is someregain of energy, which may be of the order of 20 percent to 30 percent,or more, of the pressure drop which was sustained across the venturithroat section 3. The saturated gas stream and the wetted particulatesare continuously discharged from the lower end of the diffuser tube 4 ata high velocity such that most of the particulates and excess water iscaused to impact with the liquid interface in the collection zone 7. Forexample, the stream leaving the lower end of diffuser tube 4 may be ofthe order of 4,000 feet per minute and the mean velocity reaching thegas-liquid interface at the top of the sump section 7 may be of theorder of 2,500 feet per minute.

In order to preclude the liquid level in sump section 7 from beingexcessive, there will be a constant withdrawal of slurry from the outletmeans 8 and, where desired, a suitable liquid level controlling meansassociated with the lower end of the housing 5. The present embodimentof FIG. 1 indicates a slurry withdrawal line 14 that connects withsuitable pump means 16, which in turn discharges into line 17, withvalve 15, for effecting a recycle of slurry to the upper end of the unitand into the venturi funnel section 2. In this instance, slurrydischarge from the unit is indicated by way of line 38 and valve 39 withthe latter being controlled responsive to a liquid level control systemLLC. Also, liquid make-up for the system is indicated as being made byway of line 40 and valve 41 into the slurry recycle line 17.

In accordance with a novel feature of the present improved system, thereis effected a reversal in direction for the gaseous stream leaving thelower end of the diffuser tube 4 such that the gas stream necessarilypasses upwardly through a multiplicity of mobile contact elements 18maintained in a contact zone 19. In this instance, there is shown alower perforate plate 20 and an upper screen or perforate retainer plate21. In operation, the upflowing gaseous stream with liquid droplets andsome remaining entrained particles will cause the turbulent randommotion of the light weight fluidizable fluid contact elements 18 in thepresence of a descending liquid flow maintained from spray nozzles orother distributor means 22. The latter are spaced around and aboveannular contact zone 19 so as to provide a uniform distribution ofcontact liquid through the entire zone and in turn insure the desiredcountercurrent scrubbing effect over the surfaces of all of themultiplicity of elements 18. The distributors 22 are indicateddiagrammatically as depending from an internal distributor or headermeans 23 which in turn connects with a suitable liquid inlet line 24having control valve means 25.

The gaseous stream reaching the upper end of the annular contact zone 19preferably passes through or over a flow deflecting means, such as aplurality of spaced vanes 26 which are arranged in a radial pattern toprovide a spiralling or spinning flow for the upwardly moving gas streamwhereby there is a resulting spin-out of any entrained water droplets tothe inside wall surface of zone 27 prior to the discharge of the cleanedgas stream by way of outlet means 10. In other words, the vanes orspinner means 26 will provide a further deentrainment of water in theelongated upper spin-out section 27 and such water that is collectedalong the inner wall of the housing portion of housing 5 will drain downinto the lower portion of the unit through the mobile packing stage 19.

The spheres or other contact elements which are maintained in the secondstage contact section 19 of the multiple stage scrubber system may be ofa size generally from about /z inch to about 3 inches in diameter, withthe optimum size being selected with regard to the size of the chamberor the size of the contact section being used in the system. There maybe a variety of shapes and sizes and various materials for the elements;however, conventionally they will consist of plastic hollow spheres orhollow balls being formed from a thin polypropylene wall or skin. Thesespherical shapes may of course be made of foamed polystyrene or ofperforated polyethylene such that there is some additional surface arearesulting from internal surfaces of each element. The spheres arepreferably of low density so that they will respond readily to the upflowing gaseous stream and can be easily fluidized and maintained in arandom motion. Actually they can move up and down between the spacedperforate members in the housing, but normally will be prevented fromcontacting the upper perforate member of any one section by virtue ofthe downward liquid flow. Generally, the contact elements will have adensity of less than about pounds per cubic foot and preferbaly bewithin a range of about 2 pounds to about 1 1 pounds per cubic foot. Onthe other hand, where corrosive gaseous streams are encountered or wherethere is a high temperature stream which may be excessive forpolypropylene types of materials, then it may be advisable to use hollowspheres or other types of contact elements which are formed orfabricated to have a low density and are made from stainless steels,aluminum, magnesium and the like.

In order that the elements remain ina desired random motion while thecountercurrent flow is being carried out, it is of course necessary thatthe flow rates or velocities of both the gas and liquid streams beproperly regulated. Also, generally the spheres or other contactelements will occupy less than 50 percent of the volume or open space ofa contact section. As an upper limit, gas velocities will be adjusted topreclude lifting the spheres against an upper barrier so that there maybe maintained a random motion of each of the inividual elements.Generally, gas flows through each contact section will be of the orderof 500 to 1000 feet per minute, while the liquid flowing downwardlythrough the unit will be of the order of 5 to 100 gallons per minute persquare foot of cross-sectional area. For example, in one operationhaving a liquid flow of about 45 U. S. gallons per minute and utilizingpolypropylene spheres of l l inch diameter, with the volume of thespheres comprising about 15 percent of the total volume of a contactsection, there was initial random movement of the spheres at about 500feet per minute gas velocity and no total lifting of the movable bedagainst the upper barrier for a velocity of about 800 feet per minute.

In order that suitable random motion of the spheres may be attained inany given sections, it is desirable that there be adequate spacingbetween screens or grids. For example, spacing between grids willnormally be of the order of 3 feet or more and preferably of the orderof 4 feet.

Referring now particularly to FIG. 2 of the drawing, there is indicted apartial elevational view for a modified type of two-stage system where aflexible throat section 3 is caused to be varied in cross-sectional arearespective to movement from suitable automatically operating mechanicalmeans such as cylinder means 30 in turn operating reciprocating typepiston rods 31 and constriction arms 32. As illustrated in connectionwith FIG. 1, the upper funnel section 2' carries a laden gaseous streamalong with a sutable quantity of scrubbing liquid down into the throatsection 3' to effect high velocity, high energy wetting of particulateswhich in turn will carry on down stream through an elongated diffusersection 4 to permit liquid and particle collection in a lower sump orslurry collection zone. A second stage ofliquid scrubbing in a turbulentcontact element scrubber zone will again have an upward gas flow in amanner similar to that previously described.

Diagrammatically, there is indicated the use of suitable pressure tapmeans 33 and 34 across the throat of the venturi such that there may bea continuous indication of pressure drop occuring in the venturi sectionof the unit whereby the area of the throat section 3 may be regulated tomaintain a desired constant pressure drop through the system. Adifferential pressure controller means 35 is shown connecting withpressure taps 33 and 34 through the respective lines 36 and 37 such thatthere may be the automatic regulation and adjustment of cylinder means30 by suitable hydraulic lines, air lines, or other conventonal means,to in turn provide for the desired adjustment of piston rod means 31 andthroat moving elements 32.

For the collection of substantially uniformly sized fine particles,which may be plus-micron or sub-micron in size, there will generally bea substantially fixed setting for the venturi throat section; however,where gas and liquid flow rates may vary somewhat then the cylinder andpiston means will adjust to in turn cause a variation in thecross-sectional area through the venturi throat section and maintain thedesired substantially constant pressure drop through the venturi stage.On the other hand, as pointed out hereinbefore, where the unit is toaccommodate varying sized fine particulates, there may be an adjustmentof the flexible throat section so it can be decreased in size andprovide higher pressure drop where more finely divided particles are tobe passed through the unit in a laden gas stream. Conversely, the throatsection may be enalrged to accommodate a gaseous stream carryng largersized particulates inasmuch as less pressure drop seems to be requiredto effect an efficient scrubbing in a venturi type scrubbing system.

It will be noted that the embodiment of FIG. 1 provides an axial postionfor the venturi section within a housng such that there is resultingannular shaped second stage scrubbing zone for accommodating the movablecontact elements 18 in the second stage counter-current scrubbingsection. However, in a modified construction of the system, there may bea side by side relationship and still provide for a 180 reversal in thegas flow from the lower end of the venturi diffuser and upwardly throughthe second stage contact section. In other words, the mobile packing,such as spheres 18 may be retained in an upflow path lying adjacent thediffuser tube means, rather than encompassing it, whereby the streammoves in a resulting U" flow down through the first stage venturisection and upwardly through the mobile packing section. It will beobvious that still other mechanical modifications may be made withinvarious portions of the entire system, as, for example, different kindsof vanes and deflector means may be utilized in lieu of the radiallypositioned deflector plate means 26 to effect the desired spiral flow ofspin-out of water droplets in a deentrainment section ahead of thecleaned gas outlet means. In any case, it is preferred, in accordancewith the present invention, to preclude the use of mesh or other blankettype mist extraction means, as well as to preclude the use of fixed-bedor packed contact zones, so that there is the elimination of anysections with will require periodic cleaning of entrapped particulates.

EXAMPLE OF OPERATION As a specific example of the operation of thetwostage high energy venturi-scrubber system, there may be the scrubbingof a hot gas stream in the 400 to 600F. temperature range carryingentrained time particles from a kiln. The laden gas stream will carrydown through the unit to enter the venturi funnel at a velocity of theorder of 3,300 feet per minute. Recirculated slurry is introduced intothe top end of the funnel, at a rate of approximately 10 gal/1000CF ofsaturated gases. The liquid slurry is obtained from the lower end of theunit, and may contain some 20 percent to 30 percent of solids in therecirculated slurry stream carrying down into the funnel section.

Preferably, the pressure drop through the venturi section is of theorder of inches of water for this particular service which will in turninsure an approximate 99 percent collection efficiency. By utilzing anelongated diffuser tube from the venturi throat section there may be anenergy regain of the order of to 30 percent so that there is only anoverall approximate 10 to 12 inches of water pressure drop for thestream leaving the venturi diffuser section. The velocity of the mixedphase stream contacting the liquid level of the slurrry collection zoneat the lower end of the unit is of the order of 2,500 feet per minute sothat a majority of the wetted solid particles are deposited andentrapped in this lower sump section. The reverse upward flow of the gasstream through the enlarged cross-sectional area provided by the mobilecontact elements in the second stage of scrubbing is somewhat reducedand generally of the order of 1,000 feet per minute but may be in therange of about 500 to 1,000 feet per minute. The mobile packing in theturbulent scrubbing section may, for example, comprise light weightpolyethylene spheres of approximately 1 k inches in diameter such thatthey must be in a static depth of approximately 12 inches in a zoneproviding 3 feet to 4 feet between upper and lower retaining screens.The liquid introduced to the top of the countercurrent mobile contactelement section will be of the order of 5 to 10 gallons per minute foreach 1,000 cubic feet per minute of inlet gas. As noted hereinbefore, aparticular advantage of the countercurrent scrubbing in the presence ofthe mobile contact elements further result in a constant scrubbingtogether of such elements and the relatively large surface area thatthey provide for contact with the upwardly moving gas stream and thecontinuously descending liquid stream will carry along to the lower endof the scrubber section any entrained and wetted particulates that wouldotherwise carry upwardly to the outlet section of the unit.

As a result of the two-stage of scrubbing as provided by this presentcompact unitary system there is a highly efficient 99 percent overallremoval of both the plusmicron and sub-micron particles from the gasstream.

We claim:

1. A process for the multiple stage scrubbing and cleaning of a particleladen gaseous stream, which comprises the steps of passing such ladenstream downwardly into a wetted wall funnel section and through aventuri section form mixing zone to effect the mixing of liquid withentrained particles of the stream, continuing the downward flow of theresulting wetted stream and particles through an elongated anddownwardly extending tubular form energy regain zone, discharging thegaseous stream from the lower end of the latter with a resulting highvelocity impact force upon the surface of a body of liquid beingmaintained closely adjacent such lower end of the energy regain zone,the mean velocity of said gaseous stream at point of impact on saidsurface being of the order of 2,500 feet per minute and such as todeposit and entrap a majority of said particles in said adjacent liquid,effecting reversal in direction of flow of said stream and passing saidreversed flow of said stream upwardly through at least one superposedscrubber-mist extraction zone having a multiplicity of low densitymobile contact elements therein, and discharging a resulting cleangaseous stream from above the last said zone.

2. The process of claim 1 further characterized in that a controlledquantity of liquid from the body thereof adjacent the lower end of theenergy regain zone is withdrawn and passed to distribution means at theupper end portion of the funnel section to thereby supply the liquid formixing with the gaseous stream in venturi mixing zone.

3. The process of claim 1 further characterized in that a controlledquantity of liquid from the body thereof adjacent the lower end of theenergy regain zone is withdrawn and passed to distribution meanspositioned above the contact elements in said scrubbermist extractionzone, whereby to provide additional scrubbing liquid to such zone, andthe gaseous stream therfrom is passed upwardly through a succeedingmistextraction zone.

4. The process of claim 1 further characterized in that the gaseousstream flow rate through the scrubbermist extraction zone and thequantity of elements therein are adjusted to effect a fluidized andturbulent random motion for said elements while in the presence of anydescending liquid flow through such zone.

5. The process of claim 1 further characterized in that the gaseousstream reverse upward flow through the scrubber-mist extraction zone isat a high velocity in the range of about 500 to 1000 feet per minute toeffect turbulent random movement of said low density contact elements.

2. The process of claim 1 further characterized in that a controlledquantity of liquid from the body thereof adjacent the lower end of theenergy regain zone is withdrawn and passed to distribution means at theupper end portion of the funnel section to thereby supply the liquid formixing with the gaseous stream in venturi mixing zone.
 3. The process ofclaim 1 further characterized in that a controlled quantity of liquidfrom the body thereof adjacent the lower end of the energy regain zoneis withdrawn and passed to distribution means positioned above thecontact elements in said scrubber-mist extraction zone, whereby toprovide additional scrubbing liquid to such zone, and the gaseous streamtherfrom is passed upwardly through a succeeding mist-extraction zone.4. The process of claim 1 further characterized in that the gaseousstream flow rate through the scrubber-mist extraction zone and thequantity of elements therein are adjusted to effect a fluidized andturbulent random motion for said elements while in the presence of anydescending liquid flow through such zone.
 5. The process of claim 1further characterized in that the gaseous stream reverse upward flowthrough the scrubber-mist extraction zone is at a high velocity in therange of about 500 to 1000 feet per minute to effect turbulent randommovement of said low density contact elements.